1. Field of Invention
This invention relates to image generation, image projection, and the creation and use of a plurality of image sub-sections.
2. Discussion of Prior Art
A variety of image generating and sensing devices are widely employed in graphic display terminals, projection video systems, film projectors, photographic enlargers, scanners, and cameras. Sometimes the cost of such imaging systems can be lowered by substituting two or more relatively inexpensive components for a simple, more expensive one. For example, consider a scanning device. If a high resolution CCD (Charge Couple Device) area array is used in a camera, several smaller arrays may be used instead. These smaller arrays can be manufactured with higher yields and therefore at a lower cost. The relationships between yield, defect rate, and cost are made clearer by considering the following example: if there is a 0.5 probability that a 512.times.512 device will have at least one defect, then a 2048.times.2048 device will have a 0.9999847 probability of having at least one defect, i.e., on the average, only one defect free device will be produced out of 65536 units. If several 512.times.512 components can be made to function as a single 2048.times.2048 device, the 50% yield on components can be maintained and, perhaps, manufacturing costs significantly decreased.
Projecting devices also have characteristics which lend themselves to the application of this "divide and conquer" strategy. Large cathode ray tubes, for example, are expensive to manufacture because the supporting structure needed to maintain a large vacuum is expensive. Film-based photography represents another opportunity because film transport and development systems become disproportionately expensive as negative area is increased. Bright video projecting tubes are another example.
In order to use multiple imaging components, we must be able to convert an image from or to a plurality of composing image sub-sections. I call this process "tessellation" because the process is similar to creating a mosaic from sub-sections composed of individual porcelain tiles. When an image is projected, a plurality of image sub-sections are combined to form a single entity. When an object is scanned, an image of the object is broken down into a plurality of sub-sections. For the remainder of this document, I will simplify much of the presentation by describing tessellation in terms of projecting systems. The description of a tessellator used as a sensing device is covered in detail within the parent application Ser. No. 303,956 of which this is a divisional application.
Let us consider the physical position of these tessellated sub-sections generated within a projecting system. If the sub-sections are physically adjacent to one another at the point of generation, then the generators must necessarily abut one another. Current technology has been unable to produce buttable LCD displays, CRT's, or similar projecting devices. Therefore, out of necessity, designs have separated the tessellated image sub-sections from one another. This separation can be accomplished in a variety of ways, using for example, multiple lenses or half-silvered mirrors. Heretofore, such systems have been costly, difficult to manufacture, difficult to align, and they have distorted the image in unacceptable ways. The present invention overcomes these disadvantages and thus demonstrates a projecting tessellator that is inexpensive, easy to manufacture, and of a design whose image distortion is easily corrected. Alignment is generally easy to effect, but the means of doing so depends upon specific implementation details and system requirements.